Electrical system



E. S. LAMMERS, JR.

ELECTRICAL SYSTEM.

APPLICATION FILED NOV. 16, 1911.

1 ,406,565, Patented Feb. 14, 1922. qm imiyg I I 5w I91) l o o o o E /2 o o o o 5 a o o o WMMMMJ 9 0 o Ffyi 6 20 o WITNESSES:

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BY e 7 lNVENTOR [aw/ 75. [0)772770317)? UNITED STATES PATENT OFFIQE.

EDWIN S. LAMMERS, J R., OF WILKINSBURG, PENNSYLVANIA, ASSIGNOR TO TESTING- HOUSE ELECTRIC &. MANUFACTURING COMPANY, A CORPORATION OF PENNSYL- VAN IA.

ELECTRICAL SYSTEM.

Specification of Letters Patent.

Patented Feb. 14, 1922.

Application filed November 16, 1917. Serial No. 202,337.

T all to 7mm it may concern Be it known that I, EDWIN S. LAMMERS, J12, a citizen of the United States, and a resident of lVilkinsburg, in the county of Allegheny and State of Pennsylvania, have invented a new and useful Improvement in Electrical Systems, of which the following is a specification.

My invention relates to systems of control for electric motors and particularly to systems of control for electric motors that serve for operating rolling mills.

One object of my invention is to provide a control system of the above-indicated character that shall control the acceleration of the motor or motors associated with the rolls of a mill in a manner to insure the acceleration oi the mill to full speed in a given length of time.

In rolling-mill work, it is desirable to have the motors, which are connected to the various sets of rolls, accelerate in the shortest possible time without any unnecessary delay. Moreover, it is essential for good op eration that the various sets of rolls be accelerated in a reliable and steady manner, whether the mill is running light or is operating on a piece of material.

In the usual control systems now in service, the motors, which are connected to the various sets of rolls, are accelerated in accordance with the current flowing through the motors. Thus, if the rolls are running light and unloaded, the mill will be accelerated in a very short length of time but, if the rolls of the mill are in any way loaded, the time for accelerating the mill will be materially increased by reason of the increased amount of current flowing though the motors. Such a method of acceleration is undesirable in rolling-mill work, by reason of the time lost when the rolls are in any way loaded.

In a control system constructed in accordance with m invention, means that is governed in accordance with the current flowing through the motors is provided for effecting acceleration of the motors in the shortest possible time, under normal operating conditions, and a second auxiliary means is provided for effecting acceleration of the motors in a predetermined length of time, in case the first-mentioned means fails to accelerate the motors to full speed.

In the accompanying drawing, Fig. 1 is 1.

diagrammatic view of a control system constructed in accordance with my invention; lug. is a diagrammatic view of the main circuits of the operating motor; Fig. 3 is a dlagram illustrating the sequence of operation of the various switches; and Fig. 4 is a plan view of one of the acceleiathm switches illustrated in Fig. 1 of the drawing? Referring to the accompanying drawing, a motor 1, embodying an armature 2, a series field winding 3, a compensating field wind ing 4 and a shunt field winding 5, is con nected in series with the resistors 6, 7 and 8 across a supply circuit 10 by means of a line switch 11 and line switches 12 and 13-. The line switches 12 and 13 respectively embodv energizing coils 14 and 15 and contact menibers 16 and 17. A plurality of resistor switches 18, 19 and 20, respectively embodying energizing coils 21, 22 and 23 and contact members 24, 25 and 26 are adapted to short-circuit the resistors 6, 7 and 8 in order to eiiect acceleration of the motor 1.

A plurality of accelerating switches 27, 2S and 29 are associated with the switches 13, 18 and 19 and are adapted to be operated thereby. The accelerating switch 27 embodies .a core member 30 having a switch member 31 connected thereto which bridges contact members 32 when in a released position. The core member 30 is normally held in a raised position by means of a coil spring 33 that is disposed between a stationary support 34 and a rod 35 which is rigidly mounted upon the core member 30. A bar 36, which is pivotally mounted intermediate its ends, is pivotally connected, near one end thereof, to the core member of the line switch 13 and is provided with suitable biturcatedarms at the other end thereof, so disposed as to compress the spring 33 and relieve the core member 30 from the action thereof whenever the line switch 13 is operated. Thus, the accelerating switch 27 is normally held in an open position by means of a coil spring 33 and, when the line switch 13 is operated, is under the control of a coil 37. The accelerating switches 28 and 29 respectively embody energizing coils 38 and 39 and contact members 10 and 11 and are controlled by the resistor switches 18 and 19, in a manner similar to the control of the accelerating switch 27 by the line switch 13.

A relay 40a, embodying an energizing coil 410, a switch member 42 and an interlock f 'mot'or'1, -whichmay be connected to a of rolls of a rolling mill or to any other 2 suitable load, isenergized and'a'ccelerated to switch as, is provided for governing various auxiliary control circuits. An overload relay it, embodying a'coi-l 45'and switchmember. 46, is provided for preventing an ab normal current flow through the motor 1. A start button 47 and astop button 18 are respectively' provided for initiating and stopping the operation of the system. a A drum controller 50 embodies contact segments 51 and 52which are, adapted to engage contact fingers 53 to 61, inclusive,

' when the controller is moved through its various operative positionsby means of a pilot motor 62. The pilot motor. 62 embodies an armature 63 and a shunt field winding 64:. The drum controller 50, which isope'ratedbythe pilot motor 62, serves for effecting acceleration of the motor 1, irrespective of the operationof the accelerating switches 27, 28'and 29.

f 'Assumim the elements of the 'system'to be in the po'sltions illustrated'in FigQ-l, the set full speedby operatingthe start button When the start button a? is closed, circuit is completed from the negative supply conductor through the switch 11, interlock switch 43, which is associated with the relay tfia,.start button 47, 'pilot motor 62 and switch 11 to the positive supply conductor.

' The pilot motor 62 is'thus energized and the drum'controller 50 advanced from the ofi 7 positionto position a.

Inposition a of the drum controller 50, a circuit is completed for the pilot motor 62 from the negative supply conductor through switches 113 and 12.

' r 7 supply conductor.

the switch 11, contact terminals 59 and 60,

which are bridged by the contact segment:

52, pilotmotor 62 and the switch 11 to the The circuit,

positive V supplyconductor. above traced through the pilot motor 62, serves forrmaintainingthe circuit of the pilot motor'until the final operating position foot the drum controller is reached, atwhich V point the contact segment 52 breaks contact 'with the contact terminals 59' and 60. 'In position a, of the drum controller, circuits are also completed for the energizing coils 4161,15 andlet oi the'relay 10a and the line The circuit for coils-14. and 15 is from the negative supply. con- 7 ductor, through theswitch 11, contact fingers 15 9 and 61- whi'ch are bridgedby the contact segment 52-in parallel through the coils 1 5 and 14C and the switch 11, to the positive 1a is from the negative supply conductor, through contact terminals 59 and 61which are 'bridgedby the contact segment 52-coil 411a, contact member 46, stop button/1S and switch 11, to the positive supply conductor.

The relay 40a is" energized to operate the inter-lock a3 andbreakthe circuit previously The circuit for the coil traced through the start button 47 and to complete a holding circuit for theycoils 41a,

15 and 1a through the switch member- 42; The holding circuit for the'coil 41a is from the positive supply conductor, through the switch 11', stop button 48, contact member 46 of the switch 4A, coil 41a, switch member 4:2 and the switch 11, to the negative supply 8, armature 2,-field windingsfi and 4: of the motor 1, contact member 16 of: the line switch 12, coil .4501, the switch at and the line'switch'l-l, to'the negative supply conductor.

When the line switch 13 is operated, the accelerating switch 27 is relievedfrom the influence. of the coil spring83 and is con trolled solely by the motor current that is flowing through the coil 37, Thus, when the motor current is reduced to a predeter minedpoint, the contact member 31 is low eredto bridge the contact members 32 and complete a; circuit througlrthe energizing coil 21 of'the resistor switch 18; The cir cuit through the coil 21 extends from the 7 negative vsupply conductor, through the switch 11, contact fingers59 and (ii-which are bridged by contact segment 52contact fingers 32 which are bridged by contact niember'31 oi theswitch 2 T-coil 21 and the switch 11, to the-positive supply conductor, Thus, the resistor switch '18 is operated to short-circuit the resistor 8 by means of the contact member 24:. Theaccelerating switch 28 is now controlled solely by the motor cur- 'rent passing through the 'coil 38. and, when the motor current is reduced to a rpredeterruined point, the contact member 10 is lowered to complete a circuit through "the energiz ng coil 22 of thc resistorj switch 19. The (311131111; of the coil 22 is from the neg ative supply conductor, through the switch 11, contact fingers 59 and til-which arcl bridged by the contact segment 52co11tact member 10,1co1l '22 and the switch 11, to the positive supply conductor. Thus, the resistor SW1tCl1'25'1S operated to short-circuit the resistorsection- 7. 7 r "When'the resistor switch 19 is operated, the accelerating switch 29 is controlled by the energizing coil 39 and, when the motor current which is passing throughthe coil 39 is reduced to predetermined point, the con- Y tact member A l is lowered to complete a circuit throu h the coil 23 of the resistor switch 20. he circuit through the coil 23 is from the negative supply conductor through the switch 11, contact fingers 59 and (ii-which are bridged by contact segment 52-contact member 11, coil 23 and switch 11 to the positive supply conductor. The resistor switch 20, by means of the contact member 26, short-circuits the last resistor 6 and permits the motor 1 to operate at full speed.

In case it is desired to stop the motor at any time, the stop button 18 is operated to break the circuit previously traced through the coil 41a of the relay 40a and thus 7 open the relay 40a for releasing the line switches 12 and 13 to open the motor circuit. In case the motor 1 draws an abnormal amount of current, the overload relay 44 is operated to break the energizing circuit of the relay elOa and thus release the line switches to break the -motor circuit.

In case the motor 1 is operating under a load of such proportions as to prevent the coils 37, 3S and 39 of the accelerating switches 27, 2S and 29 from releasing the respective contact members 31, 40 and 41, the motor 1 is not accelerated to full speed unless auxiliary means is provided. If the accelerating switch 27 is not operated to complete the circuit through the energizing coil 21 of the resistor switch 18, when the drum 50 is moved to position b by the pilot motor 62, a circuit is completed by the drum controller 50 through the coil 21. The circuit through the drum 50 is from the negative supply conductor, through the switch 11, switch member 42, contact fingers 53 and 5Swhich are bridged by the contact segment oi-coil 21 and switch 11, to the posi tive supply conductor. The resistor switch 18 is thus operated to short-circuit the resistor 8 and, in case the accelerating switch 28 fails to operate before the drum controller 50 is advanced to position (Z, the circuit for the coil 22 of the resistor switch 19 is completed through the drum controller 50. The circuit of the coil 22, that is completed through the drum controller 50, is from the negative supply conductor through the switch 11, switch member 42, contact lingers 53 and 56-which are bridged by the contact segment 51coil 22 and switch 11 to the negative supply conductor. Thus, the resistor switch 19 is operated to shortcircuit the resistor 7, and, in case the accelcrating switch fails to operate before the drum controller 50 is advanced to position 7', a circuit through the coil 23 of the resistor switch 20 is completed through the drum controller 50. The circuit for the coil 23, that is completed through the drum controller 50, is from the negative supply conductor, through switch 11, switch member 42, contact fingers 53 and 54-which are abnormal load upon the motor or for any other reason, the motor will be accelerated in a predetermined time, independent of the accelerating switches 27, 2S and 29, by means of the drum controller 50 which is operated by the pilot motor 62.

Modifications in the system and arrangement and location of parts may be made within the spirit and scope of my invention, and such modifications are intended to be covered by the appended claims.

I claim as my invention:

1. In a system of control, the combination with a motor, and resistors initially connected in series with said motor, of means comprising a plurality of resistor switches having accelerating switches associated therewith for short-circuiting said resistors in accordance with the current flowing through the motor, and means for automatically effecting operation ofsaid resistor switches independently of said accelerating switches.

2. In a system of control, the combination with a motor, a plurality of resistors initially connected in series with the motor, and a plurality of resistor switches for ex cluding said resistors from the motor circuit, of means, comprising accelerating switches, for operating the resistor switches in accordance with the current flowing through the motor, and means, comprising a motor-operated controller, for successively operating said resistor switches at the end of a predetermined time interval.

3. In a system of control, the combination with a motor, a plurality of resistors initially connected in series with the motor, and a plurality of electrically operated resistor switches for excluding the resistors from circuit, of accelerating switches, controlled by certain of said resistor switches, for operating predetermined resistor switches in accordance with the current flowing through the motor, and means, comprising a motor-operated controller, for operating said resistor switches at the end of a predetermined time interval, independently of the current flowing through the motor.

l. In a system of control, the combination with a motor, a plurality of resistors initially connected in series with the motor, and a plurality of resistor switches for excluding the resistors from the motor circuit, of means for governing the operation of said resistor switches in accordance with the current flowing through the motor,

means, comprising a motor-operated con t'roller, for operating said reslstorjswltches' in case the first mentioned means fails to operate Within a predetermined time interva'i, mi1nua1 means for initiating the'operationflof said controller; and. automatic means for stopping the operation thereof.

5. in a system of controh-the combination with at motor', a plurality ofresist'ors ini-' tially in series with said motor, and a plurality of'resistorswitchesfor excluding the -res1storsfrom the motor c11'cu1t', of-means, j COIHPIISIIlgE a plurahtyr of accelerating switches, for eiiecting operation of there sister switches in accordanoewlth the current flowing, through the motor, means comprising winotor-opereted controller, for operating 011'61'65181301 SWltOh-Sln case the first named means fails to completeitsop- -612Lt1011 Within a predetermined time inter- 1917; v I o EDWIN s. LAMMERS, JR. 

